In recent years, a network referred to as OpenFlow has been drawing attention (see Patent Literature 1 and Non-Patent Literatures 1 and 2). OpenFlow adopts a centralized-control-type network architecture in which a control apparatus called an OpenFlow controller controls behavior of switches called OpenFlow switches. More specifically, the OpenFlow controller can perform fine-grained path control by setting flow entries that define matching conditions specifying ingress ports and headers in layers 2 to 4 and that define processing contents in OpenFlow switches.
In addition, in order to integrally manage security and service quality in a network system, a network management system (NMS) and a policy server are used.
Patent Literature 1 discloses a management method used for a network managed in a centralized manner by a network manager. Paragraphs 0031 to 0032 in Patent Literature 1 describe that switches in the network operate in the same way as the above OpenFlow switches. In addition, the end of paragraph 0031 describes that a packet matching multiple flow header entries is assigned to the highest priority flow entry. Namely, the end of paragraph 0031 describes that a rule such as longest match can be used.